Going out on a limb here, could it be... ethics?

because is not proton the one doing it neither. It was the CEO on his personal account and the "praising" was about a decision in favor of good ethics and regulations (whether it turned out to be inaccurate is not proof of supporting fascist). Sometimes companies have people that are more opinionated, or are more expressive online. Their comments do reflect on the company but that's not the same as the rest of the employees or the others in leadership agree with the personal comments on any or all. In all Tuta is irrelevant to the conversation. People raised suspicion on Proton supporting the right, people investigated and the evidence points that Proton as a business, have been supporting organizations with liberal or left leaning ideals before and after these so called "scandals", something that many willfully ignore. You were presented with evidence but continue casting doubt in spite of not having any to support your claims. That's called black-and-white thinking, ignoring nuance, inability to reconsider your position after careful analysis, or just trolling. No different that other conspiracy theorists.
Trump is the worst President of the history of USA, probably already more corrupt that all other before him combined. I can criticize him and his administration to the end of the world but if I say something or anything positive about him in context, you and the others riding the Cancel-culture-ride are likely to believe I am a secret supporter of him, fascism or some ignorant shit. IMO Conservatives are wrong on most topics but one thing they are correct is the Cancel-Culture absurdity on the left, (which the right also have ironically). People just loove to have an enemy and be enraged.